Conventional electrophotographic photoreceptors include those having a single photoconductive layer and those having a laminated type photoconductive layer. Various proposals have recently been made particularly on organic electrophotographic photoreceptors comprising a charge transporting layer and a charge generating layer as a separate function type photoconductive layer in which an organic photoconductive substance is bound with a resin, etc. In this connection, various electron transporting agents to be used in the electron transporting layer have also been developed. Further, with respect to a matrix for the charge transporting agent, it has been proposed to stabilize the charge transporting agent by donor doping or by using polyvinylcarbazole, or to dissolve the transporting agent in various binder resins. For example, a polycarbonate matrix or polyester matrix is described, e.g., in JP-A-6l-233750,JP-A-6l-225151,JP-A-61-148159,JP-A-61-143764, JP-A-52-2436, JP-A-53-20930, JP-A-49-91-648, JP-A-61-103862, JP-A-60-222477, and U.S. Pat. No. 3,484,237 (the term "JP-A"as used herein means an "unexamined published Japanese patent application").
However, the so far proposed electrophotographic photoreceptors having a charge transporting agent-containing charge transporting layer are still unsatisfactory in sensitivity, particularly when applied as a positively chargeable photoreceptor.